My hosting company has enrolled this site in their beta for IPv6. All I had to do was ask.

If you have a hosted site, I highly recommend that you open a ticket asking for your site to be available via IPv6. If they don't offer it, ask for an arrival date and keep them to it. Enroll in any beta tests and so on. The more demand hosting companies see, the better.

In IPv4 there are a number of things that every sysadmin knows. I bet you recognize the following:

127.0.0.1

10.0.0.0/8

192.168.0.1

/24

/26

/32

255.255.255.255

255.255.255.0

You probably didn't even have to think hard about most of those.

So what are the equivalents in IPv6? I don't mean the direct translations, but what is the list of terms and numbers that sysadmins should know?

I recently sat down and came up with such a list. I listed things that Unix and Windows sysadmins should know. WAN/LAN network administrators need to know a lot, lot, more. This just covers common knowledge, a lot like the IPv4 list above.

Next I did what any good geek would do: I made Flashcards.

You can study them, quiz yourself, and even print them out. They make a great birthday gift (not really).

I'd like to thank Phillip Remaker Eliot Lear (both from Cisco) and Shumon Huque (from UPenn) for their help proofreading the cards. Shumon gets special thanks since I used his slides to get most of the information. Shumon will be teaching classes at Usenix LISA 2013 on DNSSEC and, of course, IPv6!

IPv6 is an entirely new protocol. It isn't IPv4 with larger addresses. It is new enough that you'll feel like you are starting over on a new planet; one that invented the internet using protocols that remind you of IPv4 but are.... different.

I find flashcards are a useful way to learn new terminology. I found these online:

Earlier today, the RIPE NCC (Réseaux IP Européens Network Coordination Centre) announced it is down to its last "/8" worth of IPv4 addresses. This means that it is no longer possible to obtain new IPv4 addresses in Europe, the former USSR, or the Middle East, ...

"There is a myth that IPv6 is only for those in Asia, but that's not true. According to new data discussed this week at an IETF conference, there are more IPv6 users in the U.S than anywhere else in the world -- coming in at 3 million. From the article: 'George Michaelson, senior R&D scientist at APNIC (Asia Pacific Network Information Centre) has a reasonable idea of what the current levels are globally for IPv6 adoption, thanks to some statistical research he has been doing. In his view, IPv6 is now a reality in terms of adoption. "I think you're used to us standing up and saying 'woe is me, woe is me, v6 isn't happening," George Michaelson, senior R&D scientist at APNIC (Asia Pacific Network Information Centre) said. "But it is actually happening, these are not trivial numbers of people that are now using IPv6 on a routine basis."'"

Your vendors: When talking with vendors do not treat IPv6 as a "would be nice". Inform them that anything you buy this year must be IPv6 capable and can't have worse performance than IPv4. New network gear and software purchased this year will probably be in your network until 2020 or longer. If you don't think IPv6 will be in your environment this year, you have to agree it will be by 2020.

Your boss: If you need help explaining this to your boss read this fine article on IPv6 migrations (The "introduction" section is all background and history, after that is all the advice.) TLDR version: Start from your ISP to your external gateway, then work your way in enabling IPv6 carefully at each step.

Lastly... if you want a fun starter project, get it enabled at your house either via your ISP or get a free tunnel.

I'm going to be extremely technical here. Sysadmins should really understand what World IPv6 Day is.

Does it mean the world is converting to IPv6 today? No. No, not at all. The upgrade requires technical planning and work. It can't happen without your help and without your knowing. Besides, the plan is to move to "dual stacked" IPv4+IPv6 on all hosts/networks and run that way for a good long time.

Does it mean my ISP is going to enable IPv6 on my connection? No. Not at all. (Seriously, folks, when was the last time your ISP added a feature without you having to beg for it first?)

So what does it mean?

You know that an IPv4 host as a DNS "A" record. Right?

You may know that an IPv6 host has a DNS "AAAA" record. (it is 4 times longer than IPv4, get it?)

Do a DNS lookup of www.everythingsysadmin.com and you'll get both an A record and a AAAA record.

A machine that is "IPv4-only" will ignore the AAAA record.

A machine that is "IPv6-only" will ignore the A record.

A machine that is "IPv4 and IPv6 dual stack" will try AAAA first.

Makes sense, right?

Macs, Windows, Linux boxes and a lot of other equipment comes with IPv6 enabled so that if you plug into a network that handles IPv6 it will just magically work. This is freakin' awesome.

It also causes a small problem.

Here's the problem. If you plug into a badly configured router, your machine might think there is IPv6. Maybe there is just for that subnet but not from that subnet to the ISP. What would a machine do in that situation? It would try the AAAA-record, and those packets would go nowhere. Eventually the machine will try the A-record, but that could be 30 seconds away. Not a happy experience.

The machines with this problem are about 0.05% of the internet. Not a lot, but not zero.

So what do sites do?

Google (for example) has AAAA-records for nearly all its services. However, if the DNS query comes over IPv4 it doesn't show you the AAAA-records. It only gives them to users that do their DNS queries over IPv6.

This is pretty cool if you think about it. If your DNS query could get to Google over IPv6, it must be safe for you to do your http over IPv6 too. Smart, right?

Google, Bing and tons of other sites do this trick.

Now that you know all that, I can tell you what "World IPv6 Day" is.

It is 24 hours where sites are going to give you the AAAA-record AND the A-record even if the DNS query came over IPv4.

That's it? Basically, yes, that's it.

How does this affect you?

You see, it isn't about the 0.05% of the users. It is about YOU and YOUR NETWORK which is causing one of those 0.05% to be in that 0.05%!

If you find a machine that is having problems, you can disable IPv6. However you should also fix whats wrong with that network. Disable IPv6 on the router or (much better) fix the IPv6 connectivity between the machine and "the internet".